Arachnoid cysts are cerebrospinal fluid covered by arachnoidal cells and collagen^[1] that may develop between the surface of the brain and the cranial base or on the arachnoid membrane, one of the three membranes that cover the brain and the spinal cord.^[2] Arachnoid cysts are a congenital disorder^[3], and most cases begin during infancy; however, onset may be delayed until adolescence.^[2] The International Statistical Classification of Diseases and Related Health Problems (commonly known by the abbreviation ICD) is a detailed description of known diseases and injuries. ... The following codes are used with International Statistical Classification of Diseases and Related Health Problems. ... // Q00-Q99 - Congenital malformations, deformations and chromosomal abnormalities (Q00-Q07) Congenital malformations of the nervous system (Q00) Anencephaly and similar malformations (Q01) Encephalocele (Q02) Microcephaly (Q03) Congenital hydrocephalus (Q04) Other congenital malformations of brain (Q05) Spina bifida (Q06) Other congenital malformations of spinal cord (Q07) Other congenital malformations of nervous... The International Statistical Classification of Diseases and Related Health Problems (commonly known by the abbreviation ICD) is a detailed description of known diseases and injuries. ... The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. ... The Mendelian Inheritance in Man project is a database that catalogues all the known diseases with a genetic component, and - when possible - links them to the relevant genes in the human genome. ... The Diseases Database is a free website that provides information about the relationships between medical conditions, symptoms, and medications. ... eMedicine is an online clinical medical knowledge base that was founded in 1996. ... Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. ... Cerebrospinal fluid (CSF), Liquor cerebrospinalis, is a clear bodily fluid that occupies the subarachnoid space in the brain (the space between the skull and the cerebral cortex—more specifically, between the arachnoid and pia layers of the meninges). ... Tropocollagen triple helix. ... A sketch of the human brain by artist Priyan Weerappuli, imposed upon the profile of Michaelangelos David. ... The Arachnoid mater is one of the three layers of the meninges, interposed between the dura mater and the pia mater and separated from the pia mater by the subarachnoid space. ... The Spinal cord nested in the vertebral column. ... A congenital disorder is a medical condition that is present at birth. ...

Classification

Arachnoid cysts can be intracranial (in the cranium), or on the spine. Intracranial arachnoid cysts usually occur adjacent to arachnoidal cistern.^[4] Spinal arachnoid cysts may be extradural, intradural, or perineural and tend to present with signs and symptoms indicative of a radiculopathy.^[4] Cranium can mean: The brain and surrounding skull, a part of the body. ... The vertebral column seen from the side Different regions (curvatures) of the vertebral column The vertebral column (backbone or spine) is a column of vertebrae situated in the dorsal aspect of the abdomen. ...

Symptoms and signs

Patients with a cysts may never show symptoms, even in some cases where the cyst is large ^{[citation needed]}. Additionally, the symptoms experienced are not unique to this disease. Therefore, while the presence of symptoms may provoke further clinical investigation, symptoms independent of further data cannot--and should not--be interpreted as evidence of a cyst's existence, size or location.

Symptoms vary by the size and location of the cyst(s), though small cysts usually have no symptoms and are discovered only incidentally.^[2] On the other hand, a number of symptoms may result from large cysts:

• Cranial deformation or macrocephaly (enlargement of the head), particularly in children ^[5]
• Cysts in the suprasellar region in children have presented as bobbing and nodding of the head called Bobble-Head Doll Syndrome.^[5]
• Cysts in the left middle cranial fossa have been associated with ADHD in a study on affected children.^[6]
• Headaches^[2]. While the most common symptom^{[citation needed]}, a patient experiencing a headache does not necessarily have an arachnoid cyst.
  • In a 2002 study involving 78 patients with a migraine or tension-type headache, CT scans showed abnormalities in over a third of the patients, though arachnoid cysts only accounted for 2.6% of patients in this study.^[7]
  • A study found 18% of patients with intracranial arachnoid cysts had non-specific headaches. The cyst was in the temporal location in 75% of these cases.^[8]
• Seizures^[2]
• Hydrocephalus (excessive accumulation of cerebrospinal fluid)^[2]
• Increased intracranial pressure^[2]
• Developmental delay^[2]
• Behavioral changes^[2]
• Hemiparesis (weakness or paralysis on one side of the body) ^[2]
• Ataxia (lack of muscle control) ^[2]
• Pre-senile dementia^[9], a condition often associated with Alzheimer's disease
• In elderly patients (>65 years old) symptoms were similar to chronic subdural hematoma or normal pressure hydrocephalus^[10]:
  • Dementia
  • Urinary incontinence
  • Hemiparesis
  • Headache
  • Seizures

Macrocephaly, a type of cephalic disorder, is a condition in which the head circumference is larger than average for the age and sex of the infant or child. ... DISCLAIMER Please remember that Wikipedia is offered for informational use only. ... A headache (medically known as cephalalgia, sometimes spelled as cephalgia) is a condition of pain in the head; sometimes neck or upper back pain may also be interpreted as a headache. ... This article is about the medical term, epileptic seizure, as distinct from psychogenic non-epileptic seizure. ... Intracranial pressure, or ICP, is the pressure of the brain, Cerebrospinal fluid (CSF), and the brains blood supply within the intracranial space. ... Mental retardation (abbreviated as MR), is a term for a pattern of persistently slow learning of basic motor and language skills (milestones) during childhood, and a significantly below-normal intellectual capacity as an adult. ... Hemiparesis is the partial paralysis of one side of the body. ... Ataxia (from Greek ataxiā, meaning failure to put in order) is unsteady and clumsy motion of the limbs or trunk due to a failure of the gross coordination of muscle movements. ... There are other articles with similar names; see Dementia (disambiguation). ... A subdural hematoma (SDH) is a form of traumatic brain injury in which blood collects between the dura (the outer protective covering of the brain) and the arachnoid (the middle layer of the meninges). ...

Location-specific symptoms

The following list of location-specific symptoms should be interpreted in the context of what they represent: results from several independent, unrelated studies. As of September 2006, no research has been published that comprehensively maps physical and neuropsychiatric symptoms to a specific arachnoid cyst location.^[9]

• A supratentorial arachnoid cyst can mimic a Ménière's disease attack.^[11]
• Frontal arachnoid cysts have been associated with depression.^[12]
• Cysts on the left temporal lobe have been associated with psychosis.^[13] A left fronto-temporal cyst more specifically showed symptoms of alexithymia.^[14]
• Cyst on the right sylvian fissure resulted in new onset of schizophrenia-like symptoms at age 61.^[15]
• A patient with a cyst on the left middle cranial fossa had auditory hallucinations, migraine-like headaches, and periodic paranoia^[8]
• Patients with left temporal lobe cysts had mood disturbances similar to manic depression (bipolar disorder)^[16]

In anatomy the supratentorial is located above the tentorium cerebri. ... Ménières disease (or syndrome, since its cause is unknown) is named after the French physician Prosper Ménière, who first reported that vertigo was caused by inner ear disorders in an article published in 1861. ... Psychosis is a generic psychiatric term for a mental state in which thought and perception are severely impaired. ... Alexithymia is a disorder characterized by cognitive-emotional deficits including: problems identifying, describing, and working with ones own feelings, often marked by a lack of understanding of the feelings of others; confusion of physical sensations often associated with emotions; few dreams or fantasies due to restricted imagination; and concrete... Lateral sulcus The lateral sulcus (also called Sylvian fissure or lateral fissure) is one of the most prominent structures of the human brain. ... The middle fossa, deeper than the anterior cranial fossa, is narrow in the middle, and wide at the sides of the skull. ... The auditory system is the sensory system for the sense of hearing. ... A hallucination is a false sensory perception in the absence of an external stimulus, as distinct from an illusion, which is a misperception of an external stimulus. ... For other senses of this word, see paranoia (disambiguation). ... Manic depression, with its two principal sub-types, bipolar disorder and major depression, was first clinically described near the end of the 19th century by psychiatrist Emil Kraepelin, who published his account of the disease in his Textbook of Psychiatry. ...

Cause/Etiology

Arachnoid cysts are most often developmental or related to trauma.^[4]

Diagnosis

Diagnosis of arachnoid cysts usually only occurs after symptoms are present, and many with the disorder never develop symptoms. Or, in some cases, arachnoid cysts are found incidentally. ^[17]

Diagnosis may include a mini-mental state examination (MMSE), a brief questionnaire-based test used to assess cognition.^[9] The mini-mental state examination (MMSE) or Folstein test is a brief 30-point questionnaire test that is used to assess cognition. ... Look up Cognition in Wiktionary, the free dictionary. ...

Pathophysiology/Mechanism

Treatment/Management

Treatment for arachnoid cysts occurs when symptoms present themselves.^[2] A variety of procedures may be used to decompress (remove pressure from) the cyst.

• Surgical placement of a shunt:^[18]
  • An internal shunt drains into the subdural compartment.^[19]
  • A cystoperitoneal shunt drains to the peritoneal cavity.^{[citation needed]}
• Fenestration:
  • Craniotomy with excision^{[citation needed]}
  • Endoscope^[20]
• Drainage by needle aspiration or burr hole. While these procedures are relatively simple, there is a high incidence of recurrence.^{[citation needed]}
• Capsular resection^[10]

A 1994 study found surgery necessary for good outcome in patients >65 years old when the cysts began displaying symptoms.^[21] In medicine, a shunt is a device designed to drain excess cerebrospinal fluid from the brain and carry it to other parts of the body. ... In higher vertebrates, the peritoneum is the membrane that forms the lining of the abdominal cavity - it covers most of the intra-abdominal organs. ... A window is an opening in an otherwise solid and opaque surface through which light and, sometimes, air can pass. ... A craniotomy is a surgical operation in which part of the skull (part of the cranium) is removed in order to access the brain. ... Excision means to remove as if by cutting. It can be a euphemism for Female circumcision. ... Endoscopy means looking inside and refers to looking inside the human body for medical reasons. ... A burr hole is a neurosurgical procedure to relieve hematoma around the brain. ...

Prognosis

Untreated, arachnoid cysts may cause permanent severe neurological damage due to the progressive expansion of the cyst(s) or hemorrhage (bleeding).^[2] With treatment most individuals with arachnoid cysts do well.^[2] To meet Wikipedias quality standards, this article or section may require cleanup. ...

More specific prognoses are listed below:

• Patients with arachnoid cysts of the left temporal fossa who experienced impaired preoperative cognition had postoperative improvement.^[22]
• Surgery can resolve psychiatric manifestations in selected cases.^[23]

Look up Cognition in Wiktionary, the free dictionary. ...

Epidemiology/Prevalence

Arachnoid cysts are seen in 4% of the population.^[24] Only 20% of these have symptoms, usually from secondary hydrocephalus.^[24]

A study that looked at 2,536 healthy young males found a prevalence of 1.7% (95% CI 1.2 to 2.3%). Only a small percentage of the detected abnormalities require urgent medical attention.^[25] In statistics, a confidence interval (CI) is an interval between two numbers, where there is a certain specified level of confidence that a population parameter lies. ...

History

References